Naked Broomrape – A Fascinating Parasitic Plant

British Columbia is home to a number of spectacular broomrapes like naked broomrape (Aphyllon uniflorum). These beautiful parasitic plants are easy to miss because of their size. However, once you know what to look for they can be found regularly. Understanding the connection between the parasite and the host plant is an important factor in locating and identifying different species of broomrape. Naked broomrape grows on southeast Vancouver Island, the southern Gulf Islands, and southern British Columbia.

The common name “broomrape” has its origin from the name of a British species that is parasitic on Scotch broom (Cystisus scoparius). Naked broomrape also has similarly unappealing names like one-flowered cancer root and one-flowered broomrape. Don’t be deterred by its name—this parasitic plant is definitely worth looking for!

Naked Broomrape (Aphyllon uniflorum)
Naked Broomrape (Aphyllon uniflorum) at Comox Lake Bluffs on Vancouver Island, British Columbia.

Beautiful Naked Broomrape

Despite the name, naked broomrape is a beautiful little plant. The single purple flower initially suggests plants that are in the Figwort family. However, these plants belong to Orobanchaceae. The family name Orobanchaceae references the plant’s parasitic nature and is from the Greek orobos which means “vetch/clinging plant” and anchien which means “choke/strangle”. Typically associated with the genus name Orobanche, there is a movement to place new world broomrapes in the genus Aphyllon.

Between 5cm to 10cm tall, one-flowered broomrape is small and often overlooked. Because they are parasitic, they lack chlorophyll and noticeable leaves. As a result, the plants are only visible when they are in flower which is typically in the spring. Flowers are purple to yellowish white and trumpet-like in appearance, with a singular flower at the end of a leafless stalk that is glandular-hairy. The species name uniflora refers to this characteristic. Another distinctive feature is the bright yellow stamens of the flower which contrast with the purple petals.

Naked Broomrape (Aphyllon uniflorum)
Naked Broomrape (Aphyllon uniflorum) flower detail.

Search for Host Plants to Find this Unique Flower

A good strategy to locate this unique plant is to look for host plants which will usually be larger and more obvious. Naked broomrape is holoparasitic and it has specialized roots called haustoria that pierce the roots of nearby host plants, robbing them of water and nutrients. One-flowered broomrape is parasitic on stonecrops, saxifrages, and plants in the sunflower family. As a result, it is usually found growing near these plants.

Oregon Stonecrop (Sedum oreganum)
Oregon Stonecrop (Sedum oreganum), host plant for Naked Broomrape

At Comox Lake Bluffs naked broomrape was growing in association with Oregon stonecrop (Sedum oreganum). Most of the broomrapes photographed were beside the path that follows the lakeside from the trailhead to the ecological reserve. A few additional plants were visible beyond the fence at the edge of the ecological reserve. The dry, steep, south facing slopes above Comox Lake are ideal habitat for this unique plant and the sedum that it is parasitic on. Look for one-flowered broomrape in moist, open sites or forest openings as well.

Comox Lake Bluffs
Comox Lake bluffs.

The Comox Lake Bluffs are an excellent destination for botany and unusual plants. The shoreline trail gives good access to a variety of the same plants that bloom in the ecological reserve. If you plan your visit for the spring, you might be lucky to find naked broomrape quietly blooming near the Oregon stonecrop and other host plants. Make sure to take the time to enjoy this unique and beautiful little parasite!